Lane departure warning and avoidance (LDW) systems have been developed to aid vehicle drivers in maintaining proper lane alignment by providing a warning if lane markings are crossed, some LDW systems provide timely warnings prior to crossing of lane markings.
Present LDW systems typically utilize radars, digital maps, camera/video processing sensors or other suitable sensor arrangement to detect lane markings that define a lane boundary. The detected lane markings determine the lateral position of a vehicle in a lane. Present LDW systems further usually have an analyzer for analyzing the crossing of lane markings, and suitable means for warning a driver of lane departure as necessary. An estimated time for lane crossing may be determined, and when this time falls below a predefined threshold, a warning is typically issued.
However, in order to obtain a comfortable and efficient driving of a vehicle, it is often desired to cross lane marking in a curve if possible due to the traffic situation, reducing the curvature of the vehicle's path. In this case warnings from an LDW system would constitute non-relevant warnings that unnecessarily distract the driver.
The documents U.S. Pat. No. 7,561,032 and US Publication No. 2005/273264 describe LDW systems that adapt to different styles of driving, and suppress warnings when found appropriate. However, it is desired that a higher degree of safety is obtained, while maintaining the possibility to reduce the curvature of the vehicle's path without receiving unnecessary warnings.
It is therefore an object of the present invention to provide a device for warning a driver in the event of expected or occurred lane marking crossing, which allows driving safety to be improved and at the same time the number of unnecessary warnings to be minimized.
The object is achieved by means of a lane marking crossing warning system for a vehicle in accordance with this invention. The warning system described herein includes:
a sensor arrangement arranged to detect at least one lane marking line that defines a corresponding lane boundary;
a control unit arranged to determine if the vehicle has entered a curve; and
warning means, arranged to issue a warning.
When the control unit has determined that the vehicle has entered a curve, the control unit is arranged to determine if an imaginary sensor line running a certain distance from the lane marking line has been crossed by the vehicle. In that case, the control unit is furthermore arranged determine that a warning is to be issued by the warning means.
The above object is also achieved by means of a method for lane marking crossing warning in a vehicle, where the method includes the steps:
detecting at least one lane marking line, determining if the vehicle is travelling in a curve and, if the vehicle has been determined to travel in a curve, issuing a warning to a vehicle driver if an imaginary sensor line, running a certain distance from said lane marking line, is crossed by the vehicle.
According to an example embodiment of the invention, each sensor arrangement includes a camera device.
According to another example embodiment, the control unit arranged to determine if the vehicle has entered a curve based on input from:
the sensor arrangement and/or
a steering wheel angle sensor and/or
a vehicle yaw sensor and/or
a digital map system.
According to another example embodiment, when the control unit has determined that the vehicle has entered a curve, the control unit is further arranged to move each sensor line, from coinciding with said lane marking line, to running said certain distance from said lane marking line.
According to another example embodiment, for a curve turning to the left with regard to a vehicle travelling direction, the control unit is arranged to move at least one sensor line to the left. Correspondingly, for a curve turning to the right with regard to the vehicle travelling direction, the control unit is arranged to move at least one sensor line to the right.
Other examples are disclosed herein.
A number of advantages are obtained by means of the present invention. Mainly, a lane marking crossing warning system is provided, which system allows driving safety to be improved while the number of unnecessary warnings is minimized.